Ceramic Femoral Resurfacing Head With Anti-Rotation Fixation
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Solution Overview
Problem
Conventional metal-on-metal femoral resurfacing hip prostheses pose health risks due to metal ion release and detachment issues, and they do not adequately match patient anatomy, leading to stress shielding and bone resorption.
Innovation Solution
A ceramic femoral resurfacing head prosthesis system with varying convex outer contact surfaces and stems, designed to match patient anatomy, reduces metal ion release and enhances adhesion, using ceramic materials that are harder and less prone to fracture, with asymmetrical profiles and anti-rotation elements to improve stability and reduce stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal-on-metal femoral resurfacing is used, then the prosthesis provides structural strength and durability, but metal ions are released causing allergic reactions and adverse health effects
Solution Approach 1:
The patent changes the material parameter from metal to ceramic, fundamentally altering the chemical composition to eliminate metal ion release while maintaining the mechanical properties required for hip resurfacing. The ceramic material provides comparable strength without the harmful metallic ion release that causes allergic reactions and adverse health effects.
Solution Approach 2:
The patent employs advanced ceramic materials with composite structures that combine hardness, strength, and biocompatibility. These ceramic composites replicate the load-bearing capabilities of metal while eliminating the harmful metal ion release, achieving both structural integrity and biological safety.
2Strength
If the adhesion area between the prosthesis and bone cement is increased, then the bonding strength is improved, but the prosthesis complexity increases
Solution Approach 1:
The patent employs a spherical contact surface design that naturally maximizes the contact area between the prosthesis and the prepared bone surface. This curved geometric approach increases adhesion area and bonding strength without requiring complex additional structures or components, as the spherical shape inherently provides optimal surface contact when seated on the prepared femoral head.
3Strength
If the bone volume within the head prosthesis is maximized, then stress shielding and bone resorption are minimized, but the prosthesis design complexity increases
Solution Approach 1:
The spherical geometry of the prosthesis head naturally distributes mechanical stresses evenly across the bone-cement interface and into the surrounding bone structure. This geometric design minimizes stress concentration and prevents stress shielding effects that would otherwise lead to bone resorption, while maintaining a relatively simple overall prosthesis structure.
4Adaptability or versatility
If multiple prosthesis configurations are provided to match patient anatomy, then the adaptability is improved, but the device complexity increases
Solution Approach 1:
The patent divides the prosthesis system into modular components with standardized interfaces, allowing different head sizes and stem configurations to be combined systematically. This segmentation enables multiple anatomical matching options without requiring entirely different prosthesis designs, as components can be mixed and matched to fit various patient anatomies while maintaining a unified system architecture.
Data Source
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AI summary
A ceramic femoral resurfacing head prosthesis (110) comprises a ceramic convex outer contact surface (112) engagable with an acetabulum of a patient or an acetabular cup prosthesis and a concave inner fixation surface (114) having an inner-land portion (128), the ceramic convex outer contact surface (112) and the concave inner fixation surface (114) extending to intersect each other at a rim (116). A ceramic stem (120) projects from the concave inner fixation surface (114), and is adapted to be received by a stem bore. The concave inner fixation surface (114) includes a skirt (134) which is cylindrical or substantially cylindrical, or frusto-conical or substantially frusto-conical, and at least one circumferentially elongate recess (136) at the skirt (134).